1. Technical Field
The apparatus relates to surgical fastener applying apparatus, and more particularly to fastener applying apparatus for sequentially firing fasteners having a safety member which prevents reclamping of the apparatus after the fasteners have been fired.
2. Background of Related Art
Surgical devices wherein tissue is first grasped or clamped between opposing jaw structure and then joined by surgical fasteners are well known in the art. In some instruments, a knife is provided to cut the tissue which has been joined by the fasteners. The fasteners are typically in the form of surgical staples, however, two-part polymeric fasteners are also utilized.
Such devices can comprise two elongated members which are used to capture or clamp tissue. Typically, one of the members carries a disposable cartridge which houses a plurality of staples arranged in at least two parallel rows while the other member comprises an anvil which defines a surface for forming the staple legs as the fasteners are driven from the cartridge. The two elongated members are clamped together to capture the tissue between the cartridge and staple forming surface of the anvil. After the two members are clamped, the stapling operation is effected by a pusher which travels longitudinally through the cartridge carrying member, with the pusher acting upon the staples to sequentially eject them from the cartridge. A knife may travel with the pusher between the staple rows to longitudinally cut the stapled tissue between the rows of staples. Such instruments are disclosed in U.S. Pat. Nos. 3,079,606 and 3,490,675.
A later stapler disclosed in U.S. Pat. No. 3,499,591 applies a double row of staples on each side of the incision. This is accomplished by providing a cartridge assembly in which a cam member moves through an elongated guide path between two sets of staggered stapling carrying grooves. Staple drive members are located within the grooves and are positioned in such a manner so as to be contacted by the longitudinally moving cam to effect ejection of the staples. Other examples of such staplers are disclosed in U.S. Pat. No. 4,429,695.
U.S. Pat. No. 4,955,959 to Tomkins, et al discloses a surgical stapler for sequentially firing staples which has a locking mechanism engagable with the cam bar retainer to prevent subsequent movement of the cam bar retainer after the staples have been fired. Thus, the user is prevented from cutting tissue if the cartridge is devoid of staples. Mechanisms for preventing refiring of a spent cartridge are also disclosed in U.S. Pat. No. 4,892,244 to Fox, et al, U.S. Pat. Nos. 5,156,315 and 5,253,793 to Green, et al and U.S. Pat. No. 5,129,570 to Schulze, et al.
WO 92/10976 to Plyley, et al discloses a surgical stapler which has a safety mechanism which prevents the two elongated members, i.e., the anvil carrying section and cartridge carrying section, from being reclamped after the staples have been fired and the elongated members unclamped and separated. A safety member is positioned in the cartridge assembly and is released for movement to a blocking position upon advancement of the cam bars to fire the staples. When the elongated cartridge and anvil carrying sections are separated, the safety member moves to the blocking position to prevent reclamping of the sections. EPO application 545029 to Allen, et al discloses another type of mechanism for preventing reclamping of the cartridge and anvil sections subsequent to the fasteners being fired. In Allen, et al, the knife bar contacts the safety member to move it into the blocking position. As in Plyley, the cartridge and anvil sections need to be separated in order for the safety mechanism to move to the blocking position.
The need exists for an improved safety mechanism which would prevent reclamping of the anvil and cartridge on body tissue after the staples have been fired. This would advantageously inform the user that a new cartridge needs to be reloaded in the apparatus. Furthermore, by preventing reclamping, the user would not actuate the firing knob to advance the knife to cut tissue in the absence of a loaded cartridge. It would be advantageous if such safety mechanism would move to the blocking position without having to fully separate the cartridge and anvil sections.